Tuyere with elongated outlet port



4, 9 CHIYOJI SAKAI ,678

TUYERE WITH EL'ZNGATED OUTLET PORT Filed April 5, 1966 Imam-=2. CHI You/ ssuoq/ ATT'QR HEY United States Patent 40/22,277 US. Cl. 266-41 Int. Cl. C21b 7/16 9 Claims ABSTRACT OF THE DISCLOSURE A tuyere comprising a continuous tubular wall forming an oval outlet port. A portion of the wall lying at one end of the major axis of the outlet port is longer than the portion of the wall lying at the opposite end of that axis. The inner surface of the wall portions diverge from each other in the direction of the port. The inner surface of the opposite wall portion diverges from the centerline of the tuyere at a geater angle than does the inner surface of the long wall. The inner surfaces of the wall portions at opposite ends of the minor axis may converge toward the outlet port.

This invention relates generally to tuyeres such as are typically employed to provide :air under pressure to a blast-furnace, and more particularly to an improved design therefor.

A widely recognized problem in the art relating to blast furnaces is the limitation in iron production placed on such furnaces by the inability of the furnace to accept increased quantities of air without increasing the operating pressure. Increased pressure in the furnace causes unstable conditions such as slipping, hanging, or bridging which in turn effect the production rate, coke rate, and composition of the iron produced.

Past attempts to increase the quantity of air to be admitted to the blast furnace without unduly increasing the operating pressure have generally been directed to increasing the permeability to gas flow in the stack column of the furnaces by means of intensification of uniformity of grain size, high top pressure operation, oxygen enrichment, steam addition, or fuel injection.

Little attention has been paid to the structure of the tuyeres or openings in the furnace, through which the air is admitted. The tuyeres presently employed on blast furnaces cause the gas produced in front of the tuyeres to ascend straight up through the furnace so that dead spaces are formed in the bosh between tuyere raceway outlines, or the so-called combustion zones, created in front of the individual tuyeres. This effects the gas flow pattern inside the furnace, reducing the amount of air which can be admitted to the furnace as well as causing inefficient employment of that air.

The present invention, therefore, provides tuyeres having a novel structure which permits gases in front of the tuyeres to flow in a uniform distribution covering the entire horizontal area of the lower bosh so as to eliminate the dead spaces. The improved gas flow in the bosh permits greater quantities of air to be admitted to the furnace without increasing the operating pressure, thus maintaining stable operating conditions in the furnace, and increases the utilization of the air and the resulting furnace gas.

The tuyere of the present invention is adapted to be positioned in a conventional manner in the furnace wall with the inlet end mounted in a cooling casing, and the outlet port extending into the bosh of the furnace. Briefly, the tuyere comprises a continuous tubular wall forming an elongated outlet port. The minor axis of the elongated port is formed by axially opposite portions of the wall which converge towards the center line of the tuyere at the outlet port. The major axis of the elongated port is also formed by two axially opposite portions of the wall. One of the portions is longer than the other. The inner surface of the longer wall portion diverges away from the inner wall of the axially opposite portion of the wall in the direction of the outlet port while the inner surface of said opposite wall portion diverges away from the center line of the tuyere in the direction of the outlet port at an angle, which exceeds the angle between the inner surface of said longer wall portion and the center line. The term center line referred to in this paper means the horizontal line passing through the center of the inlet port of the tuyere toward the axis of the furnace.

The inner surfaces of the wall of the tuyere thus formed guide the air admitted to the furnace in a thin layer spreading laterally. The admitted air enters the area between the inner periphery and the center of the furnace and is homogeneously distributed below the bosh. Thus, gases generated in front of the tuyeres form consolidated continuous tuyere raceway lines without dead spaces between the tuyeres and cause a turning movement of the gases in the fusion zone which adds to the uniform distribution of the gases. This increases the amount of air which may be admitted to the furnace without increasing the operating pressures thereof and increases the efficiency of utilization of this air.

For a better understanding of the invention, reference is made to the specification below and the drawings forming a part thereof in which:

FIGURE 1 is a perspective view of the present invention;

FIGURE 2 is a vertical cross sectional view of the tuyere shown in FIGURE 1, taken along the line 22 of that figure and viewed from the direction of the arrows associated with that line;

FIGURE 3 is a horizontal cross sectional view of the tuyere shown in FIGURE 1 taken along the line 3-3 of that figure and showing the invention as viewed from the direction indicated by the arrows associated with line 33;

FIGURE 4 is a vertical cross sectional view of another embodiment of the invention taken along the line 44 of FIGURE 5 and FIGURE 5 is a horizontal cross sectional view of the embodiment of the invention shown in FIGURE 4 taken along the line 5-5 of that figure.

Referring now to the figures, there is shown in FIGURE 1, a tuyere of the present invention indicated by the numeral 10. Tuyere 10 is generally tubular shape and is formed by the wall 12 comprised of copper or other material commonly used for the construction of such elements.

Tuyere 10 is provided with a base 14 for mounting the tuyere on the wall of the furnace. Base 14 contains an inlet port 16 for receiving air into the tuyere. Both base 14 and inlet'port 16 may be substantially circular in cross section.

The other end of tuyere 10 forms an outlet port 18 through which the air is admitted to the furnace. In accordance with the present invention, port 18 is elongated in shape, having a major axis and a minor axis. Referring to the figures, FIGURE 2 shows the details of the tuyere along the minor axis 20 of outlet port 18, and in particular, that the portions 22 and 24 of wall 12 at either end of the minor axis have their inner surfaces inclined inwardly from base 14 toward the center line 25 of tuyere 10. FIGURE 3 shows the details of tuyere 10 along the major axis of outlet port 18. The portions 26 and 28 of wall 12 at opposite ends of the major axis are of different lengths so that the vertical plane of outlet port 18 bisects the center line 25 of tuyere 10 at some angle other than the perpendicular, as shown in FIGURE 3. Specifically, wall portion 26 may be termed the short wall portion and portion wall 28 the long Wall portion. The inner surface of long wall portion 28 is more or less parallel to the center line 25 of tuyere 10 while the inner surface of short wall portion 26 diverges either from base 14 or from midway between base 14 and outlet port 18 away from the center 'line 25 of the tuyere. This forms the major axis 30 of outlet port 18. The inner surface of long wall portion 28 may either converge on or diverge from the center line of tuyere in the direction of the outlet port at an angle up to approximately 15 which must be lesser than the angle at which the inner surface of short wall portion diverges away from the center line. The amount of divergence of the inner surface of short wall portion 26 with respect to the center line or to the inner surface of long wall portion 28 depends generally upon the size of the furnace and the number of tuyeres installed therein.

The configuration of the outlet port 18 may be oval, rectangular, or other desired shape. It has been found desirable, however, to limit the minor axis to about 70% of the major axis.

Tuyere 10 may contain cavity 32 between the inner and outer surfaces of wall 12 through which a coolant such as water, is circulated to cool the tuyere. In the preferred embodiment of the invention, the edges of outlet port 18 are rounded to enhance the cooling effect producted by the circulating coolant.

The following specific dimensions form a typical embodiment of the present invention. Wall portions 22 and 24 converge inwardly on the center line 25 of tuyere 10 to form a minor axis 80 mm. in length at outlet port 18. The diverging inner surface of short wall portion 26 and the inner surface of long wall portion 28 parallel to the center line 25 of tuyere 10 form a major axis of 160 mm. at outlet port 18. Short wall portion 26 diverges from the center line 25 of tuyere 10 at an angle of approximately 20. Short wall portion 26 is 230 mm. in length while long wall portion 28 is 320 mm. long. This causes the plane of outlet port 18 to intercept the center line 25 of tuyere 10 at an angle of approximately 65 A plurality of tuyeres 10 are inserted in the furnace wall 33 in approximately the orientation shown in FIG- URE 1 with base 14 in contact with the cooling casing (not shown) of the wall. It will be appreciated, that all the tuyeres are inserted in the furnace wall in the same orientation. For example, all the tuyeres may be mounted with long wall portions 28 on the left hand side when viewing the tuyeres from the front. If desired, the tuyeres may be arranged in stages in the furnace.

By employing the tuyeres of the present invention, the air issuing from outlet portion 18 extends in a laterally divergent manner. As a result, the air tends to spread laterally in a thin layer and to produce gases in a thin layer. This enlarges the tuyere raceway lines in the area between the furnace wall and the furnace center while providing gases with a turning movement in the tuyere Zone and fusion zone. The formation of dead spaces between the tuyeres is avoided, permitting a greater quantity of air to be admitted to the furnace without increasing the operating pressure.

FIGURES 4 and show a modified structure of the tuyere wherein wall portion 22 is of greater length than wall portion 24 thereby to direct the flow of gas towards the hearth area, resulting in more homogeneous distribution of gases and concentration of heat in the hearth, in addition to the advantage of retaining the gases for a longer period of time in the furnace.

The preferred vertical inclination of the plane of outlet port 18, as shown in FIGURE 4, is in the order of 20 to a normal to the center line of tuyere 10. This angle may vary depending on factors such as the length of the portion of the tuyere projecting from the furnace wall and the size of the hearth diameter.

The following table shows the interrelation between furnace performance and the use of the novel tuyeres 10 of the invention as compared to the corresponding data obtained by the use of conventional ones. A 300- ton blast furnace of conventional profile, with a total height of 18 m., a hearth diameter of 4.9 m. and an inner volume of 326 m was employed for the tests and was provided with 12 tuyeres.

TABLE Test No.

Tuyeres Oonven- Novel Novel Novel Novel tional Wind volume, m. /min 500 520 530 540 550 Oxygen enriched, m. /min 27 27 27 27 27 Wind temperature. C 1000 1000 1000 1000 1000 Wind pressure, g./c1n. 933 912 887 871 863 Variation in wind pressure 1,* g./cm. 220 150 100 90 Wind pressure/ wind volume ratio 1. 77 1. 70 1. 59 1. 53 1. 49 Number of burden per day. 199 222 227 251 256 Number of hanging per day l 0 0 0 0 Number of slipping per day 13 8 5 3 0 Top gas temperature, C. 198 191 181 152 00/002 ratio of top gas" 1. 25 1. 23 1. 21 1.18 1.11 Coke rate, kgJt. iron 449 452 451 453 438 Fuel addition, kg./t. iron. 66 62 59 53 45 Iron production, t./day. 650 734 751 821 843 Production ratio 2,

t./day/m. 1. 99 2. 25 2. 30 2. 52 2. 59 Iron analyses:

Si, percent 55 51 52 54 56 Variation 3* of Si,

percent 55 46 32 30 26 S, percent 037 031 030 033 032 Variation 4* of S,

percent 049 022 026 018 018 Travelling time, hr 5. 2 4. 6 4. 5 4. 1 4. 0 Midway stack wall temp C 811 783 722 721 581 Bottom brick temp, 0.. 636 610 594 592 572 *1: Difierence between maximum and minimum.

*2: Ratio of iron output in ton to furnace volume in m *3, *4: Ditference between maximum and minimum.

Test No. 1 Was conducted with conventional tuyers at a blowing rate of 50O /min. and test Nos. 2, 3 and 4 were conducted with novel tuyeres 10 of the invention to determine the effect of the tuyeres produced on the furnace performance while admitting increased quantities of air to the furnace, the ores and wind temperature being kept unvaried.

During the period of the test No. 1, the furnace refused to take more wind when operating pressure iridicated 933 g./cm. at the blowing rate of 500 m /min. This was accompanied by frequent hanging. On the contrary, the operating pressure decreased as the quantity of air admitted to the furnace increased until the full capacity of the blower was reached during the periods of the test Nos. 2, 3 and 4, thus attaining the objects of the invention. The decreased operating pressure improved stability of the furnace operation and decreased or reduced slipping and hanging, variation in wind pressure and iron analyses, and CO/Co ratio of top gas. Further, a higher degree of utilization of furnace gas, faster travelling time, and lowered temperatures of the stack and hearth lining were obtained. More irons of better qualities were produced with less fuel by blowing more wind by virtue of the tuyeres in accordance with the invention, while providing improvements in almost every phase of conventional blast furnace operations.

It will be understood, of course, that modifications can be made in the preferred embodiment of the invention described herein without departing from the scope of the invention as defined by the appended claims.

I claim:

1. A tuyere comprising a continuous tubular wall forming an elongated outlet port having a major and a minor axis intersecting at the center line of the tuyere, said axes having opposing wall portions lying at opposite ends thereof, the portion of said wall lying at one end of the major axis being longer than the portion of said wall lying at the opposite end of the major axis, the inner surfaces of both of said wall portions diverging from each other in the direction of said port, and the inner surface of said wall portion lying at the opposite end of the major axis diverging from the centerline of said tuyere in the direction of said port at an angle which exceeds the angle between the inner surface of said long wall portion and said centerline.

2. The tuyere of claim 1 wherein the inner surface of said long wall portion is inclined from the center line of the tuyere in the direction of the outlet port at an angle up to 15.

3. The tuyere of claim 1 wherein said elongated outlet port has a minor axis and the wall portions on opposite ends of the minor axis converge toward said port.

4. The tuyere of claim 1 wherein the length of said minor axis is 70% or less of the length of the major axis.

5. The tuyere of claim 1 wherein the inner surface of said wall portion lying at the opposite end of the major axis diverges from the center line of the tuyere in the direction of said port at an angle of up to 45.

6. The tuyere of claim 1 wherein the wall portions on opposite ends of the minor axis are of difiering lengths,

thereby to cause the plane of said outlet port to be inclined at an angle from a normal of the center line.

7. The tuyere of claim 6 wherein the plane of said outlet port is inclined at an angle of approximately 20 from a normal of the center line.

8. The tuyere of claim 1 wherein the lengths of said long wall portion and said wall portion lying at the opposite end of the major axis are such as to cause the plane of said outlet port to intersect said center line at an angle of approximately 65.

9. The tuyere of claim 1 wherein the outlet port has substantially round edges.

References Cited UNITED STATES PATENTS 2,074,507 3/1937 Henry 266-41 2,602,661 7/1952 Even 266-41 2,124,437 7/ 1938 Steinbacher 266-41 2,394,497 2/ 1946 Steudel 266-41 2,495,264 1/ 1950 Kreulen 266 3,350,084 10/1967 Lucarell 26641 J. SPENCER OVERHOLSER, Primary Examiner.

ROBERT D. BALDWIN, Assistant Examiner. 

